In the field of magnetic heads to be mounted on a magnetic recording device such as a hard disk drive (HDD), recently, perpendicular recording method has become a predominant recording method in order to improve recording density with respect to a magnetic recording medium such as a hard disk. The perpendicular recording method provides not only a high linear recording density but also an advantage that the recording medium after recording is less influenced by thermal fluctuation.
As the perpendicular recording magnetic head, there has been known a magnetic head with a write shield film around a write magnetic pole, for example, as disclosed in U.S. Pat. No. 6,954,340. Between the write magnetic pole and the write shield film, there is disposed a magnetic gap film of a non-magnetic material. The write shield film has a function of preventing some of magnetic fluxes emitted from an end face of the write magnetic pole, which spread along directions other than the direction perpendicular to the surface of the magnetic medium, from reaching the magnetic medium. Such a magnetic head with a write shield film is called a wrap-around structure and capable of achieving much higher recording density.
The production process of a magnetic head with such a wrap-around structure includes after forming, on one face of a non-magnetic film made of an inorganic non-magnetic material such as alumina, a main magnetic pole film with a body portion of a large plane area and a write magnetic pole portion elongated in a plane area, the step of wet etching the one face of the non-magnetic film. Then, it also includes the steps of covering at least both sides of the write magnetic pole portion with a magnetic gap film and then wrapping the write magnetic pole portion with a write shield film through the magnetic gap film. The write shield film is generally formed by plating.
The step of wet etching is included mainly for lowering the surface of the non-magnetic film, on which the main magnetic pole film is formed, so that a write shield film can be formed with a required thickness. At this wet etching step, an undercut forms around the body portion and also beneath the write magnetic pole portion in the form of a hollow.
Since wet etching causes a hollow undercut beneath the write magnetic pole portion of an elongated plane area, as described above, the supporting strength of the write magnetic pole portion decreases, which may cause breakage of the write magnetic pole portion when a slight force is applied thereto at a resist peeling step or a foreign material removal step associated with the magnetic head production process of this type.
In addition, since the undercut is also formed around the body portion, when backfilling the surroundings of the body portion with a non-magnetic film such as alumina after wet etching, backfilling at the bottom of the undercut formed around the body portion may not be performed sufficiently, causing a heterocomponent within the non-magnetic film.
Moreover, when sputtering a seed film for plating, the seed film may not be sufficiently applied to the undercut formed around the body portion, leading to a plating defect.
One means for solving the above problems is to decrease the amount of wet etching, but since formation of a write shield film with a required thickness demands an appropriate amount of wet etching, there is a limit to decreasing the amount.